The couple enjoyed a Royal Easter Show before letting their hair down at the beach, where Kate looked pretty in a white dress by Australian designer, Zimmerman.
The couple watched a display of life-saving skill to the celebrate the work of volunteers, who have saved around 200 lives every year for the last 25 years at Manly Beach.
It was a chance for the couple to let their hair down after visiting a nearby children's hospice, Bear Cottage.
During her hospice visit, Kate thanked Australia for the warm welcome she and baby Prince George have received during their tour of the Commonwealth country.
She also spoke in praise of the many people, from prime minister Tony Abbott to thousands of screaming well-wishers, who have greeted the Cambridges since their tour began a few days ago.
After touring Sydney's Bear Cottage - one of just two children's hospices in Australia - the Duchess described the centre as a "haven" that was "inspirational".
Kate, who is royal patron of East Anglia's Children's Hospice (Each), gave a speech at the end of her visit and told the children, staff, supporters and parents: "If I may, I would also like to take this opportunity to thank everyone who has welcomed me and George so incredibly warmly on our first visit.
"To be here together as a family has been very special and we will always remember it with fond and happy memories."
Kate and Wills are enjoying a 10-day tour of Australia following their visit to New Zealand, where Kate beat William in two yachting races (see below).
Kate and William in sailing race in New Zealand
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